1. Field of the Invention
This invention relates to blocking the flow of air through the central passageway of an unused teat cup when a vacuum is applied thereto, the teat cup being fluidly connected to one or more of the remaining teat cups of a milking machine.
2. Description of the Prior Art
Prior to milking a cow with an automatic milking machine, her teats are inserted into the resilient liners of the teat cups with one teat occupying each cup. The teat-receiving central passageways of these liners are fluidly interconnected so that a vacuum can be applied sumultaneously at the end of each teat, permitting milk to flow to a milk receiver. A resilient liner is used so that this vacuum action can be shut off intermittently by applying a pulsating vacuum to the annular space between the liner and the hard outer shell of the teat cup, thereby aiding in the milking operation.
Occasionally, one of a cow's teats, due to disease, excessive medication, or injury, cannot be milked. Typically, two or three cows in every 30 have at least one such teat which, if it were milked automatically with the others, would contaminate the entire milk supply. When only three teat cups of a miling machine can be employed, the flow of air through the liner of the fourth unused teat cup must be shut off. Otherwise, a vacuum cannot be held on the teat cups in service; and they fall from the animal to the floor. To shut off this flow of air, diarymen in the past have resorted to kinking the section of vacuum hose connected to the stem of the unused teat cup. But this approach damages the hose which, being very stiff, must be twisted considerably to stop the flow of air. Further, a diaryman must constantly watch each cow having a kink in one of these hoses during a milking operation since a kink can be readily lost when she kicks or moves about.